Thermal relay and method of making the same



A. J. MOTTLAU 1,710,782

April 30, 1929.

THERMAL RELAY AND METHOD OF MAKING THE SAME 2 Sheets-Sheet 1 Filed Dec. 3,925

INVENTOR fluyusfl Moff/au WITNESSES:

W [a y 1 M Q I ATTO'RNEY April 30, 1929. A. J. MOTTLAU THERMAL RELAY AND METHOD OF MAKING THE SAME 2 Sheets-Sheet 2 Filed Dec. 8, 1925 Hy. Z

INVENTOR fluyusf J. Moff/au Illllll.

rlllllllll ATTORNEY Patented Apr. so, was.

FlQ

AUGUST J. IVIOT'I'LAU, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE ELECTRIC 85 MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

THERMAL RELAY AND IVZETHOD OF MAKING THE SAME.

Application filed December simple and easily practiced method of constructing a thermally actuable device having high electrical resistance combined with mechanical strength and ruggedness.

Fleretofore. such thermal relays have been constructed by soldering together slotted bimetallic strips in such manner that they were electrically in series clrcuit. flns method was found to be ditiicult to carry out by reason of the fineness of the work required and the relays gave trouble by reason of the melting of the solder when overheated.

In practicing my invention. ll form the bimetallic unit from a single blank into sections having integral connectingportions 0 and so fold the sections as to provide a unitary multiple section structure. With this arrangement, the use of soldered joints is avoided. Fig. 1 of the accompanying drawings is a bodving my invention.

v 2 is a plan view of the folded punching.

Fig. 3 is a side elevational view of the folded punching shown in Fig. 2.

Fig. 4 is a plan view of a modified form of punching embodying my invention.

Fig. 5 is a plan View of the modification shown in Fig. 4 in its folded position.

Fig. 6 is a side elevational view of the modification shown in Figs. 4 and 5.

Fig. 7 is a plan view of the dies and punching for embodying another modification of my invention.

Fig. 8 is an end elevational view of the punching of Fig. 7 in folded position.

Fig. 9 is a side elevational view of the modification shown in Figs. 7 and 8.

. Fig. 10 is a plan view of a modifiedform of die used in producing the punching shown in Figs. 8 and 9 and y Fig. 11 is a plan view of the dies and punchings embodying a further modification of my invention. I

In one form of my invention, 1 take a continuous narrow strip of bimetal 1, as shown in Fig. 1, and by means of dies 2 and 3 form it into slotted sections 4, 5 and 6 connected by integral straight portions 7 and 8. The connecting portions are then return plan view of the dies and the punching em- 8, 1925. erial No. 74,027.

bent on the broken lines 9 and 10 and the sections placed one ahoyethc other, as shown in Fig. 2. by the following method. lteferring to Fig. 1, the connecting portion 7 is folded on broken line 9 and again on broken line 10 in such manner that the section 1 is parallel and coextensive with section 5 and the two metals have the same relative positions in each section.

The connecting portion 8 is then folded on broken line 11 and again on broken line 12 in such manner that section 6 is superposed on section 5 and the several sections are parallel and coextensive. This folding process is continued until the desired number of sections are assembled into a unit. Strips of insulating' material 13 are then inserted between the sections to insure a tortuous path for electrical current the resulting structure being shown in Figs. 2 and 3.

This method may be modified by punching sections having several slots as shown in Figs. 4 and 5 or by folding two strips of sections in parallel to increase the electrical conductivity, as shown in Fig. 6.

In a modification of my method, I take a relatively wide strip of himetal 14:, as shown in Fig. 7, and punch therefrom lateral sections 15, 16 and 17 having slots 18, 19 and 21 and integral connecting necks 22 and 23. The connecting necks are return bent and the several sections are superpbsed by the following method. The neck portion 22 is folded downward on broken line 27 and upward on broken line 26 so that the section 15 is parallel and coextensive with section 16 and the two metals occupy the same relative positions in each section.

The neck portion 23 is then bent similarly by being folded'downwards on broken line 25 and upwards on broken line 24 in such manner that section 17 is approximately parallel and coextensive with sections 15 and 16, as shown in Fig. 8. hen the desired number of sections have been folded upon each other, insulating members 28, 29, S1. 32 and 33 arcinserted between the connecting necks and the sections and the whole clamped by insulating plates 34 and 35. held by bolts 36 and 37. linsulating buttons 38 and 39 are inserted between the ends of adjacent sections to transmit the force exerted by each section to the others. The assembled device is shown in Fig. 9.

This method maybe modified somewhat by punching two strips of sections from the same sheet by a compound die as shown in Fig; 10, thereby utilizing the material more efficiently than in the case shown in Fig. 7.

In the modification shown in Fig. 9, the

hin'ietal sections are so spaced apart by means .necting necks only. The cross-section of the current path is relatively small by reason of the thinness of the material and the fact that the current conductingsections are narrow. Tlms, it is evident that the resistance of a bimetal unit constructed by the method herein described may be made relatively high by using a current path of proper length so that suflicient heat will be generated even at low .currents to properly operate the device of which the bimetal unit may bea part.

My invention is not limited by the specific structures illustrated and changes may be effected therein Without departing from the spirit and scope thereof as set forth in the following claims.

I claim as my invention:

1. A thermally actuated device comprising a slotted bimetallic strip folded to provide a plurality of sections.

be had by slot-- 2. A thermally actuated device comprising a slotted bimetallic strip folded to provide a plurality of coextensive integral sections located in adjacent parallel planes.

3. A thermally actuated device comprising a folded bimetallic sheet, the respective metals of which occupy the same relative positions in the several folded portions.

4. A thermally actuateddevice comprising a plurality of bimetal sections folded from an integral stamped sheet.

'5. A thermally actuated device comprising a plurality of return-bent integral sections of bimetal strip folded to bend in thesame direction responsive to temperature changes and spaced apartto insure heat dissipation therefrom.

6. A thermally actuated device comprising a slotted bimetallic strip folded to provide a plurality of coextensive integral sections located in parallel planes, the respective met als of which occupy the same relative positions in the several integral sections.

7. A thermally actuated device comprising a. folded bimetallic sheet, the respective metals of which are so disposed that the bending of each of the layers, incident to temperature changes, is effected in the same direction.

8. A thermally actuated device comprising a plurality of integral bimetal sections disposed in parallel layers, the respective metals of which occupy the same relative positions in the several layers, and means for mechanically connecting said layers at predetermined points.

In testimony whereof, I have hereunto subscribed my name this 17th day of November, 1925.

AUGUST J. MOTTLAU. 

